Audio Recording Software

For PCs:

Sony Creative Software - Super Duper Music Looper
Sony Creative Software - Downloads - ACID XPress 5.0
FL Studio Homepage
Audacity: Free Audio Editor and Recorder (Mac and PC) (free)
Microsoft Photo Story 3 for Windows: make show-n-tell cool again (free)
Use Photostory to make enhanced podcasts with images.
Kid Pix® Deluxe 4 for Schools(Mac and PC) Kid pix has a narration function so students can design a slide show with images and narration that can be exported as a quicktime file which can then be uploaded as an enhanced podcast.
Podiumis a PC-based application, designed specifically for the education market. It is an easy-to-use piece of software that allows students of any age to create, edit and publish podcasts all from the same simple interface.
Jokosher is a simple yet powerful multi-track studio. With it you can create and record music, podcasts and more, all from an integrated simple environment.

For Macs:

Apple - iLife - GarageBand (free)
Voice Candy | Potion Factory
Lets you record your voice with different effects added.
Cast Life
"Whether you are creating a Podcast for your school or making a Photocast to share your child’s moments, we made sure Cast Life’s interface is fun and easy to use."
Rogue Amoeba - Audio Hijack: Record any audio on Mac OS X

Online:

Myna online audio editor
Use Myna to remix music tracks and audio clips. Apply sound effects and record your own voice or instruments (closest to GarageBand I have found)